$ 16^{\frac{3}{4}}$
Explanation: $= \left(16^{\frac{1}{4}}\right)^{3}$ To simplify $16^{\frac{1}{4}}$ , figure out what goes in the blank: $\left(? \right)^{4}=16$ To simplify $16^{\frac{1}{4}}$ , figure out what goes in the blank: $\left({2}\right)^{4}=16$ so $ 16^{\frac{1}{4}}=2$ So $16^{\frac{3}{4}}=\left(16^{\frac{1}{4}}\right)^{3}=2^{3}$ $= 2\cdot2\cdot 2$ $= 4\cdot2$ $= 8$